Background: The risk of stent thrombosis (ST) following drug-eluting stent (DES) implantation may extend beyond the initial period after successful implantation.
Methods: We evaluated the incidence, timing, and clinical outcomes of patients who presented with DES-related early (<or=30 days) and late (>30 days) angiographic ST. Between 1/2004 and 9/2006, a total of 1339 patients underwent DES implantation (90% using Cypher stents) at our institution. Dual antiplatelet therapy was recommended for 3 to 12 months. Clinical follow-up was obtained and adjudicated at 1 and 6 months following any ST event.
Results: We identified eight patients (0.6% of the total patients treated with DES) with definite ST. Their mean age was 67+/-13 years. Six patients (75%) were male and 37.5% (3/8) had diabetes. Acute myocardial infarction (AMI) was the clinical presentation in 87.5% of patients. Time to ST was 4 days in two (25%) of eight patients. The other six patients (75%) had late ST (>30 days). The median time to late ST was 480 days (range: 90-1080 days). Two patients had recurrent events of late ST. All cases of late ST, except one, occurred after clopidogrel treatment was discontinued. Median time from clopidogrel withdrawal to late ST was 18 months (range: 0.5-35 months). At 6 months' follow-up from the time of ST, the subsequent major adverse cardiac event (MACE) rate (including death, re-infarction, recurrent ST or need for emergent CABG) was 62.5% and overall and/or cardiac mortality rate was 12.5%.
Conclusion: We found that ST occurred infrequently (0.6%) and the majority (75%) of patients developed ST late (>30 days) and beyond the period recommended for dual anti-platelet pharmacotherapy. Major adverse cardiac events following ST are substantial at 6 months and thus deserve careful clinical attention.